Evaluation of Residual Stress on Welded Joint in API X65 Pipe Line through Nondestructive Instrumented Indentation Technique

Ji, Won-jae; Lee, Yun-Hee; Kim, Woo-sik; Kim, CheolMan; Kwon, Dongil

Journal of KWJS 2003;21(5):69-76.
Published online September 25, 2003.

[연구논문]비파괴 계장화 압입시험기법을 통한 API X65 배관 용접부 잔류응력 평가

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Evaluation of Residual Stress on Welded Joint in API X65 Pipe Line through Nondestructive Instrumented Indentation Technique

Won-jae Ji, Yun-Hee Lee, Woo-sik Kim, CheolMan Kim, Dongil Kwon

Abstract

Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive instrumented indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model. The residual stress from the indentation method was compared with that from the saw-cutting method.